Rio Hondo–San Gabriel JPA details Encanto Park stormwater capture project, $7.4 million in Safe Clean Water funding

At its Sept. 9 meeting, the Duarte City Council heard a presentation from the Rio Hondo–San Gabriel River Watershed Management Authority and consultant Kraft Water Engineering on the Encanto Park stormwater capture project, which the JPA says is needed to meet pollutant-reduction targets under the LA County MS4 permit.

Tracy Gleason, contract staff for the watershed JPA, briefed the council on the JPA’s role and the regional watershed management program, saying the JPA formed in July 2022 to coordinate projects across Arcadia, Bradbury, Duarte, Monrovia and Sierra Madre. “The goal is to reduce long-term pollutant loads in the rivers and local waterways,” Gleason said.

Courtney Semlow, director of civil design at Kraft Water Engineering, described the Encanto Park design and rationale. She said the project will divert a portion of storm drain flow into pretreatment, pump the water to an underground storage/infiltration facility and provide a secondary treatment before returning cleaned flow to the storm drain. Semlow said the project’s drainage-area footprint is approximately 189 acres and that the facility is designed to remove about 6 pounds of zinc per year — a pollutant of concern in the watershed analysis.

Funding and timeline details: Semlow said the JPA has secured roughly $7.4 million from the Safe Clean Water Infrastructure Program for design and construction (an earlier award around $2.4 million plus a recent award of just under $5 million). The JPA completed an initial study and a mitigated negative declaration under CEQA; design is expected to conclude in 2026, construction is planned to begin in winter 2026–27 with project closeout anticipated in late 2028, and the park could be closed for up to 18 months for construction impacts. Safe Clean Water Program funding also includes operations-and-maintenance support, she said.

Semlow described above-ground elements intended to limit impacts to park use: an access road for maintenance, an expanded nature walk, native plantings, regrading of the soccer field for improved drainage, ADA improvements to the parking lot and repaving after construction. She said most treatment components will be underground and visible changes will be limited to maintenance access hatches and new planting areas.

Council members asked technical and permitting questions. Council member Lewis asked about pump failure scenarios and maintenance; Kraft Engineering and JPA staff said the system is an offline diversion that will bypass treatment to the existing storm drain if pumps are inoperable and that the JPA will be responsible for operations and maintenance under legal agreements being developed. Council member King questioned why the MS4 program required treatment of local drainage and expressed skepticism about removing pollutants from what he called natural flows; the presenters clarified the drainage area comprises primarily developed streets and catch basins and that the project treats runoff before it reaches the river.

No council action was taken; staff said a public-information process is underway (outreach at the city picnic on Sept. 27 was planned) and that final funding approvals require additional JPA and board actions.